Releasing to widespread acclaim last week, AMD's next-generation Radeon RX 480 graphic card ran into choppy waters despite strong performance figures for a card in its price class. Benchmarks results were good, but in-depth testing by TomsHardware of the card's power draw flagged one potential weakness: drawing more power (at load) than it's strictly rated for.
PCI-Express specifications enforce specific upper thresholds for power draw from various sources, although the exact specs. have been difficult to tie down. The rule of thumb is that an expansion card should not draw more than 75W from the slot and 75W from each 6-Pin PCI-E connector, but additional stipulations are made regarding draw from 3.3V and 12V lines. In theory the RX480 shouldn't have an issue - it's a card rated at 150W, the reference design requires a single 6-pin connector, and it should have passed both internal and external certification tests.
First TomsHardware, and then PCPerspective, discovered that the card was drawing more than the recommended power under gaming load from both the PCI-E x16 slot and 6-pin power. Whilst TomsHardware observed spiking (millisecond) draw and 90W slot averages during stress tests, PCPerspetive's test with a low-pass-filter applied indicated long-term averages of ~80W over the slot's 12V line and ~85W from the 6-pin.
Concern has been focussed on the power draw over the PCI-E slot, mainly due to it being higher than has been observed with any performance-class graphics card. Over-spec. slot and aux. power draw are both potential causes for concern* if system components aren't up to the task, especially regarding motherboard traces and linkages.
The story was developing late into the week, and over the weekend AMD took the highly unusual step of addressing it officially:
"As you know, we continuously tune our GPUs in order to maximize their performance within their given power envelopes and the speed of the memory interface, which in this case is an unprecedented 8 Gbps for GDDR5. Recently, we identified select scenarios where the tuning of some RX 480 boards was not optimal. Fortunately, we can adjust the GPU's tuning via software in order to resolve this issue. We are already testing a driver that implements a fix, and we will provide an update to the community on our progress on Tuesday (July 5, 2016)."
- AMDJoe, AMD Representative
- AMDJoe, AMD Representative
Speculation is rife over the issues' cause but at this point only AMD are in a position to know. If a fix can be pushed via a driver update it speaks to both the flexibility of 4th Gen GCN architecture and their improved software, but there must be some concern that oblivious users will fail to update their driver as soon as possible.
Far from being discouraged however, AMD enthusiasts have turned their eyes to partner cards such as the Sapphire Radeon RX 480 Nitro OC. Designed to be overclocked from the get-go, they're supplied with an 8-pin rather than 6-pin PCI-E power connector as standard.
* Potential in that the medium to long-term effects of this level of power draw on components, especially budget motherboards, is unknown.
SOURCE: Tomshardware, PCPerspective, Reddit - 'AMD official statement'